DELHI POLICE PUBLIC SCHOOL

Lakshita mathur
Class X (D)
Roll- No. 19
METALS AND NON-METALS
ASSIGNMENT-5

SECTION-A (Objective questions)

1. Which of the following oxide(s) is/are soluble in water to form alkalies?
(i) Na₂O
(ii) SO₂
(iii) (K₂O
(iv) NO₂
(a) (i) and (ii)

(b) only (i)

(c) (ii) and

(iv) (d) only (iii)

Ans. (a) (i) and (ii)

2. The colour of thesolution observed after 30 mins of placing zinc metal to copper
sulphate solution is
(a) Blue
(b) colourless
(c) dirty green
(d) reddish brown
Ans. Blue

3. Which of the following are not ionic compounds?

(i) KCl
(ii) HCl
(iii) CCl₄
(iv) NaCl
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
 (d) (i) and (iii)
Ans. (ii) and (iii)

4. The electrical conductivity and melting point of an alloy is

(a) Less than of pure metal
(b) More than that if pure metal
(c) Equal to that of pure metal
(d) Electrical conductivity is less and melting point is more than the pure metal
Ans. Less than of pure metal

5. Food cans are coated with tin and not with zinc because
(a) Zinc is costlier than tin
(b) Zinc has higher melting point than tin
(c) Zinc is more reactive than tin
(d) Zinc is less reactive than tin
Ans. Zinc is more reactive than tin

6. Which of the following pair will give displacement reaction?

(a) NaCl solution and copper metal
(b) MgCl₂ solution are aluminium metal
(c) FeSO₄ solution and silver metal
(d) AgNO₃solution and copper metal
Ans. AgNO₃solution and copper metal

7. There are four metals K,L,M and N. Identify them by the following hints given below
K forms basic oxide, L forms amphoteric oxide , Oxide of M dissolves in water to form
alkali, N does not react with water at all
(a) K- Zn L- Al M- Na N-Fe
(b) K- Fe L- Na M- K N-Zn
(c) K- K L- Cu M- Pb N-Na
(d) K- Cu L- Zn M- K N-Pb
Ans. (b) K- Fe L- Na M- K N-Zn

In the following questions (8-10 ) a statement of assertion followed by a statement of reason is given.
Choose correct answer out of the following

a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
b) Assertion and reason both are correct statements but reason is not the correct explanation for
assertion.
 c) Assertion is a correct statement but reason is an incorrect statement.
d) Assertion is an incorrect statement but reason is a correct statement

8. ASSERTION- Zinc is used in the galvanisation of iron

REASON- Its coating on iron articles increases their life by protecting iron from rusting
Ans. Assertion and reason both are correct statements and reason is correct explanation for
assertion.

9. ASSERTION- Pure gold known as 24 carat gold is not suitable for making jewellery.
REASON- pure gold is very soft.
Ans. Assertion and reason both are correct statements and reason is correct explanation for
assertion.

10. ASSERTION- ionic compounds have high melting and boiling points
REASON- a large amount of energy is required to break the strong inter ionic attraction in ionic
compounds.
Ans. Assertion and reason both are correct statements and reason is correct explanation for
assertion.

SECTION-B (Very short answer questions)

11. Hydrogen is not a metal but it is assigned a place in reactivity series of metals. Why?
Ans. Hydrogen is included in the reactivity series because
It exhibits some metallic properties and reacts like metals.

12. Why is Al₂O₃ considered an amphoteric oxide? Explain with help of chemical equation.
Ans. Al₂O₃ is amphoteric because it reacts with-

Acids- Al₂O₃ + ₆HCl → ₂AlCl₃ + ₃H₂O

Bases- Al₂O₃ + ₂NaOH → ₂NaAlO₂ + H₂O

13. Name one metal which is extracted by

(a) Reduction with heat only
(b) Reduction with carbon
(c) Reduction with aluminium
Ans. (a) Mercury (Hg)
(b) Zinc (Zn)
(c) Chromium (Cr)
14. Why is H₂ gas not evolved out when a metal is treated with nitric acid?
Ans. H₂ gas is not evolved when a metal is treated with nitric acid because nitric acid
(HNO₃) is a strong oxidizing agent. It oxidizes the hydrogen gas (H₂) produced,
converting it to water (H₂O), before it can be released.

15. Can silver nitrate solution (AgNO₃ ) be stored in iron container? Give reason for your
answer.
Ans. No, silver nitrate solution (AgNO₃) cannot be stored in an iron container.
Reason:
Silver nitrate reacts with iron to form silver and iron(III) nitrate:

2AgNO₃ + Fe → 2Ag + Fe(NO₃)₃

This reaction causes the iron container to corrode and the solution to become
contaminated with iron ions. Additionally, the silver ions can be reduced to form
metallic silver, which can precipitate out of the solution.
Therefore, silver nitrate solution should be stored in a container made of a non-reactive
material, such as glass or plastic.
16. Why is tungsten used almost exclusively for filament of electric lamps?
Ans. Tungsten is used for electric lamp filaments due to its:
- High melting point
- High tensile strength
- Low vapor pressure
- Good electrical conductivity

17. Explain why solid sodium chloride does not conduct electricity but in the molten state it
is a good conductor of electricity.
Ans. Solid sodium chloride (NaCl) doesn't conduct electricity because its ions are fixed
in place, unable to move freely. In the solid state, the ions are held together by strong
electrostatic forces, making it a bad conductor.
However, when melted, the ions gain kinetic energy and become free to move, allowing
them to conduct electricity. The molten state breaks the rigid structure, enabling the ions
to flow freely and carry electrical charge, making it a good conductor of electricity.

SECTION –C (Short answer questions)

18. Give reasons
(a) Carbon can reduce CuO and not CaO.
(b) When copper is immersed in AgNO₃ the solution acquires a blue colour
(c) Aluminium is a highly reactive metal yet it is used to male utensils.
(d) Ionic compounds have higher melting and boiling points.
Ans.
(a) Carbon can reduce CuO (copper oxide) because CuO has a lower reduction
potential than carbon, allowing carbon to reduce CuO to copper. However, CaO
(calcium oxide) has a higher reduction potential, making it difficult for carbon to
reduce it.
(b) When copper is immersed in AgNO₃ (silver nitrate), copper displaces silver ions,
forming copper(II) nitrate, which has a blue color. This is because copper has a higher
reduction potential than silver.

(c) Aluminium is highly reactive, but it forms a thin layer of oxide on its surface,
which protects it from further reaction. This makes it suitable for making utensils, as
it resists corrosion.

(e) Ionic compounds have higher melting and boiling points because of the strong
electrostatic forces between the oppositely charged ions, requiring more energy to
break these bonds and change state.

19. Show the bond formation between

(a) MgCl₂
(b) Ca₂O
(c) NaH
Ans.
(a) MgCl₂ (Magnesium Chloride)
Mg²⁺ + 2Cl⁻ → MgCl₂
Magnesium loses 2 electrons to form a +2 ion, which combines with 2 chloride ions
(each with a -1 charge) to form a neutral molecule.
(b) Ca₂O (Calcium Oxide)
2Ca²⁺ + O²⁻ → Ca₂O

Two calcium atoms lose 2 electrons each to form +2 ions, which combine with a
single oxygen ion (with a -2 charge) to form a neutral molecule.
(c) NaH (Sodium Hydride)
 Na⁺ + H⁻ → NaH
Sodium loses 1 electron to form a +1 ion, which combines with a hydride ion (with a
-1 charge) to form a neutral molecule.

20. An element reacts with oxygen to form an oxide which dissolves in hydrochloric acid.
The oxide formed also turns a solution of red litmus blue. Is the element a metal or non
metal? Explain with the help of a suitable example.
Ans. The element is a metal.
Reasons:
1. The oxide dissolves in hydrochloric acid, indicating it's a basic oxide, which is a
characteristic of metal oxides.
2. The oxide turns red litmus blue, indicating it's basic in nature, another characteristic
of metal oxides.
Example: Sodium (Na) reacts with oxygen to form sodium oxide (Na₂O), which:
- Dissolves in hydrochloric acid (HCl) to form sodium chloride (NaCl) and water
(H₂O)
This confirms the element is a metal, as it forms a basic oxide that dissolves in acid and
turns red litmus blue.

21. Differentiate between

(a) Calcinations and roasting
(b) Ore and mineral
Ans.
(a) Calcination and Roasting:
- Calcination: Heating of ore in the absence of air to remove water and volatile
substances (e.g., decomposition of calcium carbonate to calcium oxide).
- Roasting: Heating of ore in the presence of air to convert sulfides to oxides, often
producing a more reactive form (e.g., roasting of zinc sulfide to zinc oxide).
(b) Ore and Mineral:
- Ore: A naturally occurring material from which a valuable substance (e.g., metal)
can be extracted economically (e.g., iron ore, copper ore).
- Mineral: A naturally occurring inorganic solid substance with a specific chemical
composition and structure (e.g., quartz, feldspar).
, an ore is a deposit containing a valuable substance, while a mineral is a specific
substance with a defined composition and structure. All ores are composed of
minerals, but not all minerals are ores.

22. Both Ca and Mg are heavier than water but still floats over it. Explain with the help of
chemical equation.
Ans. Ca and Mg float on water despite being denser because they react with water to
release hydrogen gas, which gets trapped, creating buoyancy:
 Ca + 2H2O → Ca(OH)2 + H₂
Mg + 2H2O → Mg(OH)2 + H₂
Trapped hydrogen gas makes them float.

23. Give reason

(a) Why copper is used to make water tanks but steel (an alloy of iron) is not.
(b) Copper cannot liberate hydrogen from HCl, Why?
(c) Carbonates and sulphides are converted into oxides during the process of extraction
Ans.
(a) Copper is used to make water tanks because it:
- Doesn't react with water (non-reactive)
- Resists corrosion
- Has antimicrobial properties
Steel (alloy of iron), on the other hand, reacts with water, leading to rust and corrosion.
(b) Copper cannot liberate hydrogen from HCl because:
- Copper is below hydrogen in the reactivity series
- Copper doesn't displace hydrogen from acid (HCl)
(c) Carbonates and sulfides are converted into oxides during extraction because:
- Carbonates and sulfides are unstable at high temperatures
- Heating them in the presence of air converts them into stable oxides
- This process is used to extract metals like zinc, lead, and copper

SECTION-D (Long answer questions)

24. A metal M which is used in thermite process, when heated with oxygen gives an oxide
B which is amphoteric in nature. Identify A and B. Write down the reactions of oxide B
with HCl and NaOH.
Ans. Metal M is Aluminum (Al) and oxide B is Aluminum Oxide (Al₂O₃).
Aluminum is used in the thermite process, a highly exothermic reaction, to
produce pure metals.
Al₂O₃ is amphoteric, meaning it can react with both acids and bases.
Reactions of Al₂O₃ with HCl and NaOH-
1. Al₂O₃ + 6HCl → 2AlCl₃ + 3H₂O (Al₂O₃ reacts with HCl to form aluminum
chloride)
2. Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O (Al₂O₃ reacts with NaOH to form sodium
aluminate)

25. Two ores A and B were taken, on heating ore A gives CO2 whereas ore B gives SO2.
What steps will you take to convert them into metals.

Ans. To convert ores A and B into metals, follow these steps:

Ore A (Carbonate):

1. Calcination: Heat ore A to release CO₂, forming metal oxide (MO).

MO + CO₂ → MCO₃ (heating)

2. Reduction: Reduce metal oxide (MO) with a reducing agent (e.g., carbon) to obtain metal M.

MO + C → M + CO

Ore B (Sulfide):

1. Roasting: Heat ore B in air to convert sulfide to oxide, releasing SO₂.

MS + O₂ → MO + SO₂ (roasting)

2. Reduction: Reduce metal oxide (MO) with a reducing agent (e.g., carbon) to obtain metal M.

MO + C → M + CO